1. Field of the Invention
The present invention relates generally to a document reading apparatus having a device which reads an image formed on a document. In particular, the present invention is directed towards a document reading apparatus having an automatic document feeding apparatus which sequentially separates a plurality of documents and reads an image from each of the documents.
2. Description of the Related Art
A known image reading apparatus, such as the image recording apparatus described in JP-A-2004-299867, includes an automatic document feeding apparatus, and a scooping guide member positioned between a transparent glass plate and an end glass plate. The known image reading apparatus also includes a reading sensor including a line CCD image pickup device which is configured to move along the lower surfaces of the transparent glass plate to position a document, such that an image may be read from the document. The known image reading apparatus further may include a contact image sensor (CIS), a paper feed tray unit, a paper discharge tray unit, a document feeding path formed therebetween, and a document feed roller positioned in the document feeding path on one side of a lid which covers the surface side of the translucent glass plate and the end glass plate.
In the known automatic document feeding apparatus, the width of the left and right side edges of the document are fed parallel to the feeding direction, and the document is not displaced sideways or fed obliquely.
In a known document reading apparatus, such as the document reading apparatus described in JP-A-2005-217509, a document is positioned on a document table having a transparent glass plate, such that a predetermined portion of the document is aligned with a document alignment mark, and the image is opposed to the document table. The known document reading apparatus includes a document holding panel for holding the document, and the image is read by a reading sensor, such as a contact image sensor or a CCD, which moves under surface of the glass plate in a predetermined scanning direction.
In the known document reading apparatus, a document holding surface of the document holding plate has a regularly repeating pattern, such as a grill pattern, such that an image processing device processes the document positioned on the glass plate and the repeating pattern as data, recognizes a portion of the repeating pattern which is hidden behind the document on the basis of the data, whereby the size, the position, and the inclination of the document is detected by a document detection device.
Nevertheless, when the configuration described in JP-A-2005-217509 is applied to the image reading unit for reading the image on the document fed by the automatic document feeding apparatus having the configuration described in JP-A-2004-299867, the width of the document may not be accurately detected.
Specifically, in JP-A-2005-217509, the reading sensor is stationary at a document reading position of the end glass plate on the lower surface side, and the document to be read moves with respect to the reading sensor. Therefore, when the document being fed has the same repeated pattern, e.g., solid black, on both side edges thereof, as the repeated pattern at the document reading position on the back surface side of the document and the corresponding portion of the document pass through the reading position, the reading sensor may not read and detect the accurate width of the document.